gauges acting up? (did a search)

[Pyro85GT]

ok first a little background info. i took the old engine out and the car sat for a few weeks. my dad hooked up a small wire from the negative post of the battery to a ground so that the alarm will still work. after putting the new engine in, i had the key in the on position and the check oil light came on. after i finally got around to putting oil in it, the light went away right afterwards. the thing that i dont get is that the actual gauges dont seem to be working. when i turn the key to the on position, the fuel level gauge rises like it usually does, but it stops at its lowest postion and the low fuel light in the little cluster under the radio stays on. i had the lines that connect to the mechanical fuel pump to the tank uncapped for those weeks, but could it be possible that an entire tank of gas evaporated through just those lines in that time? im thinking that the gauges themselves arent working since when i tried to crank the engine the voltage gauge didnt dip down like it normally does. after searching, im wondering if its the internal voltage regulator for the gauges, but why would it all of a sudden not work? ive tried looking through wiring diagrams to see if i missed anything that i missed under the hood. i left some manifold sensors off that normally control emissions equipment like the thermactor valve, etc, but are those necessary to get the gauges to work or can the IVR just stop working all of a sudden?
sorry for such a long post, but i figured too much info is better than being too vague. has anyone had a similar problem or is there some thign under the hood that i need to hook up?

TIA,
Brad

[sleepercoupe]

does your voltage gauge just stay right in the middle? how much gas did you have in it when it was sitting? your in TX so if it wasnt a ton it could be empty. easy way to check, pop your temp. sender out and put it in some VERY hot water, get some boiling and then run outside and stick it in and see if the gauge moves.

[Zap's 85 GT]

Check the gauge by grounding the sender wire to the block. The gauge should peg. This also works for the oil pessure gauge and the fuel gauge.

[Puter]

Since you had your engine out, check your grounds. These always lend to electrical gremlins. You should have a good, clean connection on the block AND the firewall. Make sure that you used a star washer to get a good bite. Make sure that the ground cable is not corroded internally. I have had cables hide corrosion and leave me suddenly stranded.

[twister]

have you checked the constant voltage regulator that mounts on the back of the cluster?

[Pyro85GT]

wow, not only quick responses, but quite a number of them. this board is great.

does your voltage gauge just stay right in the middle? how much gas did you have in it when it was sitting? your in TX so if it wasnt a ton it could be empty. easy way to check, pop your temp. sender out and put it in some VERY hot water, get some boiling and then run outside and stick it in and see if the gauge moves.

yes it stays dead center even when cranking. ill have to try the sensor trick to see if it works or not.

Check the gauge by grounding the sender wire to the block. The gauge should peg. This also works for the oil pessure gauge and the fuel gauge.

which is the sender wire? or do you mean the sender wire for each gauge such as the oil sender, etc? i havent the slightest clue where the fuel sender wire is, though. sorry if its a dumb question but i suck at electronics and am trying to remedy that.

Since you had your engine out, check your grounds. These always lend to electrical gremlins. You should have a good, clean connection on the block AND the firewall. Make sure that you used a star washer to get a good bite. Make sure that the ground cable is not corroded internally. I have had cables hide corrosion and leave me suddenly stranded.

the new AFR heads are clean so the ground there is good, ill recheck the firewall side and i reused the stock groundstrap with the star looking

have you checked the constant voltage regulator that mounts on the back of the cluster?

this i was saving as a last resort and will hopefully check it this weekend. i really want to fire this 347 up, but i dont want to do so without the gauges working. i spent too much on it to screw it up now. i saw in teh ford shop manual that there are some wires under the hood that all need to be hooked up to make the gauges work properly, but im not certain. ill recheck it tomorrow. thanks for the help guys, hopefully ill soon be posting about a fix.

[Zap's 85 GT]

Zap's 85 GT wrote:
Check the gauge by grounding the sender wire to the block. The gauge should peg. This also works for the oil pessure gauge and the fuel gauge.


which is the sender wire? or do you mean the sender wire for each gauge such as the oil sender, etc? i havent the slightest clue where the fuel sender wire is, though. sorry if its a dumb question but i suck at electronics and am trying to remedy that.

The oil pressure sender wire is the only wire going to it. It is right next to the oil filter.

The water temp wire for the gauge is at the front of the intake manifold on the right side(while looking at it from the front of the car).

Just remove the wire from the sender and press the metal against another metal engine component. You only need to have the key turned to the run position to be able to check them.

The three gauges(fuel, oil pressure, temp) are controlled by the voltage regulator on the rear of the dash. If all three are bad to the same degree and everything else seems allright, I'd suspect that its bad.

And yes, verify you have a good ground between the engine and to the body.

[Pyro85GT]

ok i grounded the oil pressure sender wire and the oil gauge started climbing, so i take it the IVR is not toast? i also flipped the firewall side of the ground strap around so it sits completely flush with the firewall just in case. the ground i would assume is good since the starter works, everything works basically except for the gauges. i couldve sworn i had read in either the haynes or chiltons that they are all connected somehow in that if one doesnt work they all dont. i am probably mistaken in thinking that, but it makes me think that something under the hood isnt connected. i have the water temp senders hooked up to the front of the intake, the one that has the little wire running to it and the other that screws into the top of the heater core outlet. the oil pressure sender is hooked up also. i left out the ones in the back of the intake that i think control the EGR and somethign else similar. what i mean is the ones with with the vacuum lines attached to them, i didnt put in the new intake. i hooked one up to the connector in the main wiring running across the firewall to see if it mattered and no dice. could one of the wires that ran to the old carb be causing any of this? the ones that ran to the drivers side of the carb i couldnt reuse and the one that ran to the choke coming off the alt wires i couldnt reuse because the holley instructions said to run a new lead from somewhere else since the stock one is usually 9 volts or so. any ideas? im so close to finally breaking this new engine in, but i refuse to do so without at least the marginal stock gauges hooked up. i want to upgrade to some good aftermarket ones later, but for now i have to use the stock ones which are better than nothing i would assume.

[Zap's 85 GT]

Just because the gauges peg out by grounding the wires, doesnt mean the voltage regulator is 100% accurate.

[Pyro85GT]

ah, that makes sense.

good news, though...the gauges apparently do work after all. my dad convinced me that there was no way the tank could have evaporated over the course of a couple weeks, but i guess it did since the gauges apparently do work. i fired up the car anyways because i couldnt resist and a second or two later the oil pressure rose up to normal. im still confused as to why the voltage gauge never dropped. it couldve been that the battery was too weak to even move the gauge, but it was apparently strong enough to crank the engine over so im still a little confused on that. the gas gauge might actually be spazzing out unless there really is no fuel in the tank, but i did add about a gallon and a half. i still have to figure that out.

on another note, the engine heated up rather quickly. i only ran it for 10 seconds or so, not enough to open the thermostat but the headers were pretty hot for only running for that short of a time. is that normal because of the rings scraping? thanks again for all your help, everyone.

[Puter]

on another note, the engine heated up rather quickly. i only ran it for 10 seconds or so, not enough to open the thermostat but the headers were pretty hot for only running for that short of a time. is that normal because of the rings scraping? thanks again for all your help, everyone.

My first thought is that your timing is off.

[Pyro85GT]

hmm, i triple checked at only 10 degrees. is it possible that the the 670 street avenger im using is jetted to lean? it wasnt insanely hot, but hotter than i thought it would get in only 15 seconds time or so.

[BetterDays]

does your voltage gauge just stay right in the middle? how much gas did you have in it when it was sitting?

My voltage gauge has never moved.
Water Temp - Well, not sure how accurate it is...
Oil Press - disconnected (running separate gauge)
Fuel Level - Either Full or Nothing in between.....

I may have to check this stuff to see what it may be....

I am looking at $500 in gauges, plus either making a new bezel or finding one to buy somewhere....

[Pyro85GT]

if i had to get a new bezel, i would definitely look into the one offered on this site. i think i would rather get it anodized black or dark grey instead of the aluminum look, but the bezel itself looks killer. i plan on doing this eventually, but funds dont permit that right now.

[Puter]

is it possible that the the 670 street avenger im using is jetted to lean? it wasnt insanely hot, but hotter than i thought it would get in only 15 seconds time or so.

I would think rich instead of lean. As if you are still burning fuel in the headers.

[Pyro85GT]

ah you know, that does make sense. i never ran it long enough for the choke to open so i guess thats possible. if the weather is good outside tomorrow and not rainy like it was today ill actually try breaking it in and seeing if the all the gauges actually are working or not.